Currently, bio-diesels are competitively developed and produced worldwide, and even in Korea, the production of bio-diesels has already begun. In addition, bio-diesels are commercially available as an additive of diesel oil.
In the procedure of producing bio-diesel, a great amount of glycerol, corresponding to about 10% of the amount of the produced bio-diesel, is generated as a by-product. However, the supply of glycerol is greater than the demand therefor and the oversupply of glycerol leads to a decrease in its value. Thus, it is economically advantageous to convert glycerol into chlorohydrins, such as dichloropropanol, which is a higher-value added product than glycerol.
Chlorohydrins, such as dichloropropanol, are used as a raw material in producing epichlorohydrin. Most chlorohydrins, which are currently supplied to the market, are manufactured from propylene. More particularly, a method of preparing chlorohydrins includes a two-stage step of preparing allyl chloride by high temperature chlorination of propylene and forming the chlorohydrin by reacting the allyl chloride with a chlorination agent using an excess amount of industrial water. However, the method of preparing chlorohydrins using propylene has problems: an instability of propylene supply and demand caused by an increased price of propylene; a production of a great amount of waste water and waste matter; and excessive initial investment costs due to the two-stage manufacturing step, which results in difficulties in the construction and modification of a manufacturing apparatus.
Accordingly, a one-stage step of directly preparing a chlorohydrin by reacting a polyhydroxy aliphatic hydrocarbon, such as glycerol, which is a by-product of bio-diesels, with a chlorination agent in the presence of a catalyst is considered as being more economical. The one-stage step using glycerol is advantageous in that: costs of raw materials can be reduced by using an inexpensive polyhydroxy aliphatic hydrocarbon; waste water and other waste can be dramatically reduced since industrial water is not used in the manufacturing procedure, and thus, the step is environmentally friendly; and initial investment costs related to the step and the environment can be reduced.
However, the method of preparing a chlorohydrin composition produces water as by-product, and the generated water inhibits a chlorination reaction of glycerol and a polyhydroxy aliphatic hydrocarbon, so that as the reaction progresses, the reaction speed gradually decreases and the reaction time increases and selectivity of chlorohydrins decreases.